I couldn’t keep my eyes open. I was sitting against a fence, shivering, my calves tied into knots and my hip flexors threatening to burst into flames, and all I wanted to do was sleep. I’d force my eyes open, take a sip from the water bottle I’d been handed after I crossed the finish line, and then my eyes would slide shut again. Open, sip, repeat.

At one point, a concerned medic approached me. “Everything OK?” he asked. I forced a smile, told him I was fine, just needed to rest, and then I gave in. I shut my eyes once more and drifted off, maybe for 30 seconds, maybe for 10 minutes. I’d never been overwhelmed by the urge to sleep after a race, but I’d also never run a full marathon. I finished (just barely) the Chicago Marathon in October, but as I sat against that fence in the chute for the Arizona Rock ‘n’ Roll Marathon, I could finally say that I had run a marathon. Well, once I woke up, I could say it.

In my first post for this Runner’s Journal series, called “Why Run?”, I laid out some of the reasons I had been drawn back to the sport I’d abandoned in the 15 years since high school. Among those reasons, I wrote:

“I run to challenge myself, to set a goal and accomplish that goal. I run to find my limits and expand them, to redefine my comfort zone, to defy that voice inside my head that tells me my legs hurt too much and my lungs can’t take any more. I run to prove to myself that I can accomplish anything if I’m willing to work hard enough.”

The 3 hours and 44 minutes I spent running through Phoenix, Scottsdale and Tempe epitomized that paragraph. It was most definitely a challenge to accomplish my goal of running a full marathon. I blew past my limits and bulldozed my comfort zone during the race, and did my best to ignore “that voice” for the final six miles or so. I set out to run the whole race, and save for a handful of quick pit stops to guzzle some water or Gatorade, I did just that, even when “that voice” was pleading for a break at mile 24. I kept my feet moving, refused to walk, and crossed the finish line almost an hour faster than I did in Chicago last October. Then I took a nap.

I won’t pretend that I accomplished anything monumentally profound last weekend. Heck, it seems everyone is running marathons and half marathons these days. But it was a significant personal achievement, a moment I won’t ever forget, a moment I once thought would never happen, and yet there I was in the chute, medal in hand, mission accomplished. I was sleeping, but I was there.

I didn’t think I could, until I did

“I run to find my limits and expand them.” In hindsight, this line is perhaps the most accurate in the above paragraph. I remember how awful I felt after finishing my first half marathon, and how fantastic I felt seven months later after my third. My body wasn’t ready for 13.1 miles in Columbus, but by Cleveland, it knew what to expect and I cruised to a PR.

Last Sunday, my body was toast. I crossed the line sore, nauseous, thirsty and exhausted, certain I couldn’t have run another 10 feet. That’s exactly how I felt after my first half marathon. Now, a 13-mile run qualifies as an easy day. Will the pattern hold next month when I hop onto a plane to run the Tokyo Marathon?

Man, I hope so.

To be clear, I’m not suggesting Tokyo will be easy just because I finished the Arizona Marathon, but it should be easier. Not only will my body be better conditioned to handle 26.2 miles, but perhaps more importantly, I now know that I can, in fact, run a full marathon. Clearing that mental hurdle is huge. Telling yourself you can do something is one thing, but proving to yourself that you can do it is another.

At the expo the day before the race, I bought a shirt that said “Inspired to Run” on the back. Those three words sum things up beautifully for me. The act of running – of hitting the pavement or treadmill several times a week, braving the elements in the dead of winter or peak of summer, logging mile after mile after mile on lonely roads and rolling trails – isn’t a whole lot of fun. It’s not easy either. But it’s damn sure rewarding.

I’ve accomplished things during these two years of running that I never thought were possible. In about five weeks, I’ll add one more item to the list when I run a marathon in Tokyo. That’s incredible to me. And it’s no coincidence that, with each mental hurdle I’ve cleared in my training, my confidence in other areas of life has soared as well, driving me to pursue other personal and professional endeavors that once seemed out of reach and unattainable.

That may sound corny, but it’s the truth. There’s a reason running has exploded in popularity over the last decade. There’s a reason I have friends and family members emailing me for beginner training tips or advice on picking their first pair of running shoes (I’m no expert on either subject, by the way). There’s a reason people like my aunt, who ran her first marathon last year at the age of 53, fall in love with the sport. She’s done a bunch of half marathons, some sprint triathlons, joined a team for Ragnar last year, and probably accomplished so many other things that I don’t even know about. She also completed her second marathon in Arizona last weekend, and was thrilled to PR by about three minutes. That’s what it’s all about.

I am a marathoner. I had to wait three months longer than anticipated to be able to say that, but it doesn’t make it any less sweet. I can’t relax yet, though, not with the Tokyo Marathon on the horizon. I’m not sure how I’ll feel when I pick my routine back up Sunday with an easy five miler, but there’s only one way to find out.

For eight miles, everything was perfect. For the next 18.2 miles, nothing went right.

I came through the first mile marker of the 2011 Chicago Marathon at about 8:05 and comfortably held a steady pace for the next seven, soaking in the energy from the incredible crowd, taking in the view of the city and thoroughly enjoying the start of my first marathon. It was a pristine morning, with the race’s 45,000 participants treated to 64-degree temperatures and a gorgeous blue sky, and my goal of savoring the moment early on instead of obsessing about my time had thus far unfolded as planned.

I crossed the eight-mile marker in just about 64 minutes and prepared to settle in for the next 12 miles, hoping to start shaving some time off my pace before hitting the final six-mile stretch. I knew I’d need to have something left in the tank to finish strong, having topped out four weeks earlier with a 21.5-mile training run, so I was planning on listening to my body to see just how much I could safely push the pace.

I didn’t like what my body had to say.

The good news? My shoulder felt fine. Actually, it felt great. I had a case of subscapular bursitis crop up the previous weekend(NOTE: the injury has since been diagnosed as nerve compression), and while it was a painful injury, I learned during a six-mile run on Thursday and a slow two miler Saturday morning that it actually felt better while running. Hoping to prevent any late-race soreness, I slapped Icy Hot medicated strips onto three different spots of my back, just to be safe. That may very well have been my first mistake of the day.

The bad news? My legs weren’t feeling nearly as good as my shoulder. At a time when I should have been finding a mid-race groove, my legs were tired. Too tired. Certainly too tired for mile 8 of a 26.2-mile race. I knew I would be pushing my body to an extreme that day, but I wasn’t ready to do it yet. Okay, I thought, I’ll just maintain pace for now and hope my legs recover in time for a strong finish. They didn’t.